Stent delivery system and method of use

Abstract

A stent deployment system and method wherein a two balloon catheter is used to expand the stent within a body lumen. The balloons are concentrically arranged about a dual lumen catheter wherein the inner balloon is smaller than the outer balloon. By first inflating the smaller balloon to expand only the center section of the stent, the stent undergoes substantially all of its longitudinal contraction before the ends make contact with the lumen tissue upon inflation of the larger outer balloon.

What is claimed is: 
     
       1. A stent delivery catheter assembly for an expandable stent, comprising: a multi-lumen catheter dimensioned to be advanceable through vasculature to a deployment site;   an inner inflation balloon, having a first preselected inflated length and diameter disposed about said catheter and in fluid communication with a first lumen formed in said catheter;   an outer inflation balloon, having a second preselected inflated length and diameter disposed about said catheter, wherein the inflated length of said outer balloon is greater than the inflated length of said inner balloon, wherein the inflated diameter of said outer balloon is no greater than said inflated diameter of said inner balloon and wherein said outer balloon is positioned to centrally contain said inner balloon; and   an expandable stent mounted on the outer inflation balloon.   
     
     
       2. The apparatus of claim 1, wherein said inner balloon is about 70% as long as said outer balloon. 
     
     
       3. The apparatus of claim 1, wherein said inner balloon is in the range of 50% to 90% as long as said outer balloon. 
     
     
       4. The apparatus of claim 1, wherein the inflated diameter of said outer balloon is less than the inflated diameter of said inner balloon. 
     
     
       5. The apparatus of claim 1, wherein said inflated length of said outer balloon is substantially equal to that of a stent to be deployed. 
     
     
       6. The apparatus of claim 1, wherein said balloons are bonded to said catheter. 
     
     
       7. A method of deploying an expandable stent within a body lumen, comprising the steps of: crimping a stent on to an outer inflation balloon containing a smaller centrally located, inner inflation balloon which are disposed about a catheter;   advancing said stent and balloon carrying catheter to a deployment site;   inflating said inner balloon to partially expand said stent; and   inflating said outer balloon to fully expand said stent.   
     
     
       8. The method of claim 7, further comprising the step of deflating said inner balloon prior to inflating said outer balloon. 
     
     
       9. The method of claim 7, wherein said inner balloon remains inflated as said outer balloon is inflated.